1. Field of the Invention
This invention relates to milling cutters and, more specifically, to a plunge milling cutter having angled pockets with a chip clearance groove to permit a greater number of inserts to be mounted within the cutter.
2. Description of Related Art
A goal of most metalworking operations is to perform a given machining task in the least amount of time and in a manner that will not result in premature tool failure. In particular, in a milling operation, it is well-known that the cutting forces upon, and the tool wear of, individual inserts within a milling cutter will be diminished if the cutting load is evenly distributed among many inserts in the milling cutter. However, in the past, milling cutter body designs have limited the maximum number of cutting inserts to be placed in the body. Utilizing a cutter with the maximum number of inserts is especially important for the machining of cam lobes on cam shafts of internal combustion engines.
U.S. Pat. No. 5,820,308 is directed to a milling cutter having a plurality of on-edge inserts mounted about the periphery of the cutter. The orientation of these on-edge inserts limits the number of inserts that will fit within the cutter body.
An object of this invention is to provide a plunge milling cutter having a greater number of cutting inserts about its periphery to minimize the force and to maximize the tool life of each insert in the milling cutter while at the same time providing effective chip clearance.
The present invention is directed to a plunge milling cutter comprising a cutter body rotatable about a central axis, a peripheral wall on the cutter body, and insert pockets located in the peripheral wall. Each pocket is spaced from an adjacent pocket by a lug and each pocket has support surfaces including a bottom surface adapted for positioning a rectangular insert within a predefined rectangular envelope within the pocket. Each rectangular envelope has a front and back and four sides therebetween, including a top side, a bottom side and a radially inward side. Each lug has a radial width, a front face extending upwardly from the pocket bottom to the top of the lug, an axial face extending downwardly from the top of the lug to a height below the top of the lug; and a rear face extending from the axial face downwardly to the bottom surface of an adjacent pocket. The support surfaces of the pocket are defined by the lug front face, the bottom surface, the lug rear face of an adjacent lug, and a pocket wall positioned radially inwardly from the peripheral wall and connecting adjacent lugs. The lug axial face is sloped downwardly across the entire lug width from the top of the lug to the lug rear face, thereby providing a chip clearance groove across the entire width of the lug. Furthermore, the lug front face extends over the entire back of the insert envelope.
The invention is further directed to a plunge milling cutter assembly comprising a milling cutter as described above and including inserts within each pocket of the milling cutter.